| 摘要 |
<p>PURPOSE:To carry out the change-over a change-over valve which will be a secondary side by use of a pressure generated in a circuit thereby to obtain a simple circuit structure and improve the maneuverability thereof. CONSTITUTION:When the operator opens the change-over valve 10a in full stroke, exhaust oil of a hydraulic pump 2 passes through pipes 15, 19 or 16, 20 and pressurized oil flows through a throttle 21. Consequently, a pressure loss takes place, and the pressure of an upstream side of the throttle becomes high and that of its downstream side becomes low. When the change-over valve 10a is made to return to its neutral position, the oil will not flow through pipe 15 or 16, and therefore a pressure difference is lost at both ends of the throttle 21. Therefore, the change-over valve 9a returns to its neutral position by means of a return spring thereof. In the case where the change-over valve 10a is controlled in a half stroke state, the exhaust oil cannot overcome the return spring of the change-over valve 9a, and the latter is held in its neutral position. Accordingly, the control of a plurality of pumps can be carried out by the maneuvering of one ordinary manual change-over valve.</p> |
